Is the military’s oath to defend the constitution or to the POTUS?
Officer's oath is the Constitution alone. Enlisted oath is to the Constitutin and to obey the orders of the President, and the officers appointed over them.
Officer's Oath:
I, A.B., do solemnly swear (or affirm) that I will support and defend the Constitution of the United States against all enemies, foreign and domestic; that I will bear true faith and allegiance to the same; that I take this obligation freely, without any mental reservation or purpose of evasion; and that I will well and faithfully discharge the duties of the office on which I am about to enter. So help me God.
Unchanged since 1868!
Enlisted Oath:
Enlisted Oath: I, ___, do solemnly swear (or affirm) that I will support and defend the Constitution of the United States against all enemies, foreign and domestic; that I will bear true faith and allegiance to the same; and that I will obey the orders of the president of the United States and the orders of the officers appointed over me, according to regulations and the Uniform Code of Military Justice. So help me God.
Last changed in 1962 to bring it more in line with the officers oath, before that in 1950 to put in the UCMJ, which didn't exist before the late 1940s creation of the Defense Department. It had previously not been changed since 1790, when both oaths were the same:
Officer and Enlisted Oath: I, A.B., do solemnly swear or affirm (as the case may be) to bear true faith and allegiance to the United States of America, and to serve them honestly and faithfully against all their enemies or opposers whomsoever, and to observe and obey the orders of the president of the United States of America, and the orders of the officers appointed over me, according to the articles of war.
That's got to be the Army Version, since the Articles of War applied to the Army, the Navy had their own equivalent.
The 1868 change to the current officer's oath was more in keeping with the original 1789 version.
Officer Oath: I, A.B., do solemnly swear or affirm (as the case may be) that I will support the Constitution of the United States.
Original 1789 Enlisted oath.
Enlisted Oath: I, A.B., do solemnly swear or affirm (as the case may be) to bear true faith and allegiance to the United States of America, and to serve them honestly and faithfully against all their enemies or opposers whatsoever, and to observe and obey the orders of the president of the United States of America, and the orders of officers appointed over me.
Source:
The Oath of Office
A Historical Guide to Moral Leadership
Lt Col Kenneth Keskel, USAF
Air & Space Power Journal - Winter 2002